Degradation of signal-to-noise ratio in counting detectors due to pile-up effects

Abstract

This work proposes a methodology to quantify how the non-linearity of counting detectors due to pulse pile-up effects impacts detrimentally the signal-to-noise ratio of measurements and the resulting DQE. The method is presented from a conceptual point of view, justified and validated by both analytical and Monte Carlo methods applied to the ideal theoretical pile-up models usually discussed in the literature. Although the motivation of this work is the application to photon counting X-ray detectors, the study may be relevant for other type of particle or radiation detection systems operating at high count rate regimes, when pile-up is not negligible. The high count rates can be managed in actual experiments by implementing pile-up compensation methods in the detector readout chain, by applying correction algorithms to the measured data or by a combination of both. What has been less discussed in literature is the impact of those pile-up compensation techniques on the final statistical properties of the resulting data, and the proposed method can be potentially used for that purpose. The application of the method to more realistic systems is illustrated with an example of a simulated 2D X-ray photon counting detector that includes all the primary physical effects and the full readout chain.

Experimental evaluation of the SNR in counting detectors under pile-up conditions

“…However, it is much less studied, to our knowledge, how the different pile-up compensation strategies impact the statistical properties of the measurements. For this reason, in a previous study [3], a method was proposed to evaluate the effective signal-to-noise ratio (SNR) of measurements obtained with counting detectors under pile-up conditions. The method was studied and validated with the ideal paralyzable and non-paralyzable pile-up response, and with a simulated counting device, implementing a model that includes physical limitations such as noise and front-end saturation.…”